Charge forming device



Aug. 14, 1934. c v MORTON 1,970,020

CHARGE FORMING DEVICE Filed Aug. 6, 1930 5 Sheets-Sheet 1 ATTORNEYS 1934. c. v. MORTON 0 1,970,020

CHARGE FORMING DEVI CE Filed Aug. 6, 1930 5 Sheets-Sheet 2 ATTORNEYS Aug. 14,1934. cfv. MORTON 1,970,020

CHARGE FORMING DEVICE Filed Aug. 6, 1930 5 heets-Sheet 3 INVENTOR W BY 5 ATTORNEYS Aug. 14, 1934. c. v. MORTON CHARGE FORMING DEVICE Filed Aug. 6, 1950 5 Sheets-Sheet 4 INVENTOR ATTORNEYS Aug. 14, 1934. c. v. MORTON CHARGE FORMING DEVICE S Sheets-Sheet 5 Filed Aug. 6, 1930 1 .ulQiT I.

N3 QQ m mm 1 mm as w on V wm fi wn Patented Aug. 14, 1934 UNITED STATES PATENT OFFICE.

CHARGE FORMING DEVICE Craig V. -Morton, Dayton, Ohio, assignor, by mesne assignments, to General Motors Corporation, Detroit, Mich.,

ware

a corporation of Dela- This invention relates to charge forming devices for internal combustion engines and more particularly to devices of this character which comprise a plurality of primary carburetors, each of which delivers a primary mixture of fuel and air to one of a plurality of secondary mixing chambers located adjacent the engine intake ports and in which the primary mixture is mixed with additional air under certain operating conditions.

Charge forming devices of this type are described in the copending applications of Fred E.

Aseltine et al., Serial Nos. 288,683, and 360,404,

filed May 2'7, 1928 and May 4, 1929, respectively,

1 and in the patent of Fred E. Aseltine, No. 1,931,-

5 599, which patent contains a diagrammatic view showing agenerally similar arrangement of fuel passages to those disclosed in this application.

The general objects of the present invention are to provide a charge forming device of generally improved construction having novel means for proportioning the fuel and air in the mixture under various operating conditions,'particularly during the acceleration period and to provide a device having a minimum number of moving parts whereby the construction is generally simplifled and manufacturing is rendered less difflcult and less expensive. v

With these general objects in view, one feature of the invention resides in the provision of separate air valves controlling the main air inlet and the port supplying air to the primary mixing chambers. The opening of the valve controlling admission of air to the primary mixing chamber is restricted and the valve is temporarily moved toward closed position by the opening of the main air valve. By means of this construction the mixture is enriched to the proper degree during the acceleration period and it has been made possible to secure this enrichment without the use of the secondary air valve and its relatively complicated controlling means which have been employed in earlier forms of this device.

A further feature is the specific construction of these valves both of which are mounted on the same stem and controlled by the same valve spring, the main air valve being fixed to the stem and the primary air valve slidable thereon.

Another feature of the invention is the much simplified mechanism for operating the primary and air throttle valves, a fuel pump and a high speed fuel valve, all of which are operated from a single operating member according tosthe present invention.

An additional feature of the invention resides in the simplified construction of the dashpot controlling the movement of the main air valve.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings, wherein a preferred embodiment of one form of the present invention is clearly shown.

In the drawings:

Fig. 1 is a fragmentary plan .view of a charge forming device constructed in accordance with this invention, showing the entire carburetor unit and a part of the manifold associated therewith.

Fig. 2 is a vertical section onthe line 22 of Fig. 1.

Fig. 3 is a side elevation of the carburetor unit viewed from the right in Fig. 1;

Fig. 4 is an elevation of the carburetor unit seen from the left in Fig. 1, partly broken away to show certain parts in section. 1

Fig. 5 is a rear elevation of the carburetor unit.

Fig. 6 is a plan of the main housing forming part of the carburetor unit viewed from below.

Fig. '7 is a plan view of the lower casting of the carburetor unit.

Figs. 8, 9 and 10 are fragmentary sections on the lines 88, 9-9, and 10-10 respectively of Fig. 2.

Figs. 11 and 12 arefragmentary sections on the lines 11-11, 12-12 respectively of Fig. 7.

Fig. 13 is a detail view of the float and float valve controlled thereby.

The device disclosed comprises a main air manifold 10 having three outlet branches, the middle branch 12 being disclosed herein, while the entire manifold is disclosed in the prior applications above referred to. Each of the outlet branches communicates with one of the ports of a multic'ylinder engine and each is provided with an attaching flange 14 for securing the manifold to the engine block in theusual manner, while a flange 16 is provided at the inlet end of the 28, in which certain fuel passages are formed, is secured in any suitable manner to the bottom of the main housing, a suitable gasket 30 being provided to prevent leakage of fuel between the two valve being provided for this purpose.

castings. A sheet metal fuel bowl 32 is held tight against an annular shoulder 34 formed on the main housing, by a screw 36 which is screwed into a part of the casting 28, suitable gaskets being provided to prevent leakage. Fuel is conducted by a conduit (not shown) to a passage 38 formed in a boss 40 formed on the main housing. The passage 38 communicates with a nipple 42 screwed into the bottom of the main housing so as to project into the float chamber and provided with a passage therethrough as indicated in Fig. 13. This passage has a restriction 44 which forms a seat with which a valve 46, operated by the float 48, pivoted at 50, cooperates to maintain a substantially constant level of fuel in the reservoir 32 in the usual manner.

Fuel is conducted from the fuel bowl 32 to a plurality of primary fuel nozzles 52, one of which is located in each of the primary mixing chambers 54, the construction of which will be more fully described later. The fuel conduit between the fuel bowl and the nozzles comprises a horizontal fuel passage 56 communicating directly with the fuel in the bowl 32 and with a vertical passage 58 which, when the casting 28 is secured to the main housing, communicates with a horizontal channel 60 formed in the bottom of said main housing. The primary fuel nozzles are screwed to the wall of the main housing and communicate at their lower ends with the channel 60 in the manner shown in Fig. 8.

Fuel is admitted from the fuel bowl to the passages 56 and 58 at all engine speeds, the flow of fuel being partially restricted by a cylindrical portion 62 of a valve 63. This cylindrical part of the valve is slightly smaller than the bore 64 in the casting 28 in which the valve is received, to permit fuel to flow around the valve through the passage 56 when the valve is in its closed position as shown in Fig. 12. This valve 62 also controls a passage 65 for admitting additional fuel at high speeds, a tapered surface 66 on the The passage 65 connects with a vertical passage 67 in which the stem 69 of the valve 62 slides and which is normally closed by the tapered portion of said valve as shown in Fig. 12, the valve being held in this position by a spring 68 which is received in the bore 64 between the valve and a plate '70 secured to the bottom of casting 28 in any desirable way. This valve is adapted to be operated in a manner fully disclosed hereinafter to open the passage 67 and admit a flow of fuel therefrom into the passage 56 to augment the flow of fuel therethrough at relatively high speeds and is guided in its movements by an enlargement '71 on the stem 69, which has a sliding fit in the passage 67, and a flange 72 at the bottom of the valve which slides within the bore 64. Each fuel nozzle is provided with a fixed restriction '73 to limitthe maximum flow .therethrough.

The primary mixing chambers comprise the anterior ends of primary mixture passages 74 which are parallel and close together as indicated in Figs. 5 and 8. When the carburetor is attached to the manifold these passages register with conduits '76 in the manifold which convey the primary mixture to secondary mixing chambers in each outlet branch of the manifold which are constructed in the manner fully disclosed in the earlier applications above referred to. A single throttle valve 78, which extends across all of the primary mixture passages, controls the flow therethrough and is provided with grooves which register with said mixture passages. This throttle is operated by mechanism more fully disclosed hereinafter. It will be noted that the middle passage 74 communicates with a conduit 76 in the form of a straight tube which projects through the middle outlet branch of the manifold as shown in Fig. 2, while the other primary mixture conduits include pipes 81 for conducting the primary mixture to the outlet branches located at the ends of the manifold as shown in the earlier applications.

All of the air entering the carburetor flows through the inlet coupling 24 and is controlled by a main air valve 82, secured to a sleeve 83 pirmed to the valve stem 84, as shown in Fig. 2, and normally held against a seat 86 by a spring 88 which engages a flange 90 secured to the sleeve 83. This spring is received between the above mentioned flange and an air valve 94 which may be termed a primary air valve and which is slidable on the valve stem 84, being normally held against a seat 96 by the spring 88 which is effective to hold both valves closed as indicated in Fig. 2, when the engine is not running. The seat 96 is an annular member which is secured in any desirable manner in an opening in the main housing as shown in Fig. 2.

The air flowing past the valve 82 enters a chamber 95, which, for convenience, is termed the secondary air chamber and air flows from this chamber through a secondary air passage 98, controlled by manually operable air throttle 100 secured to a shaft 102 rotatably mounted in the main housing, to the inlet of the manifold 10 and to the secondary mixing chambers formed in said manifold.

Air is supplied to the primarymixing chambers from a primary air chamber 104 formed in the main housing and communicating directly with all of the primary mixing chambers 54 as indicated in Fig. 2, being admitted to said primary air chamber through an opening 105, in the wall of 11 .a hole in the top of the casting 28, as indicated in Fig. 2, while the sleeve 83 which surrounds said stem at its upper end is slidably received in an opening 108 in the upper end of an inverted cup shaped member 110 which surrounds the upper end of the spring 88 and is screwed into the main housing immediately above the primary air chamber, and is open at its lower end as indicated in Fig. 2. It will be clear that on opening of the throttle, the manifold vacuum will be communicated to the primary air chamber 104 to an extent dependent upon the degree of throttle opening. This will effect opening of the primary air valve against the pressure of the spring 88. Opening of the main air valve is effected in a manner more fully described later.

The air valve 94 may be held closed to facilitate starting of the engine by the choke mechanism which includes a bell crank lever 85 having a hub 87, pivoted on a pin 89 screwed into a boss 91 projecting from the main housing. One arm 93 of the lever 85 projects through the wall of the main housing to a point above the air valve and the operating arm 85 which is entirely outside the housing is adapted to be connected to some suitable form of operating means extending to a point convenient to the operator. A spring 97 is provided between the head of the pivot pin 89 and the boss 91 to hold the choke lever yieldingly against said hub. On operation of the choke the arm 93 9f the choke lever is moved into position to be engaged by a projecting portion of a flange 99, secured to the air valve as shown in Fig. 2 and is variably positioned to permit whatever degree of valve opening is desired. The valve should not be held completely closed because some air is necessary to carry the starting fuel from the nozzles to the engine cylinders, or a' small orifice may be provided in the wall of the housing, for this purpose. Also instead of providing the flange 99, the choke lever may be bent to the right and downwardly in Fig. 2 to engage the valve direct.

The operating connections for the throttle and the valve 100 comprise a main operating arm 112 secured to one end of the primary throttle by a screw 113 and provided with pins 114 which engage corresponding depressions in the end of the throttle to prevent relative movement between said throttle and the operating arm. This arm is provided at its free end with an orifice 115 in which a Bowden wire or any other suitable operating connection may be connected. Secured to the other end of the throttle in a similar manner is an operating plate 116 provided with a pin 118 projecting therefrom to which an operating link 120 is pivotally connected. The other end of this link is provided with an orifice 121 in which is secured a pin 122 projecting from an arm 124 secured in any desirable manner to the shaft 102 on which the valve 100 is fixed. The orifice 121'is slightly larger than pin 122, in order to permit a slight play and prevent binding, while a spring 123, one end of which engages link 120 and the other end an orifice 125 in an offset part of the link 120, tends to hold the parts fixed with relation to each other. The plate 116 is rotated with the primary throttle in a, clockwise direction during opening movement of the latter and the pin 118 is so positioned that during the first part of the opening movement of the primary throttle, said pin moves substantially in an arc of a circle, the center of which is the pin 122 so that during this movement of the pin 118 there is no accompanying movement of the pin 122 and the arm 124, whereby a certain amount of independent movement of the primary throttle relative to the valve 100 is-permitted. After this, independent movement of the primary throttle further opening of said throttle will effect simultaneous movement of the arm 124 and valve 100, the parts being generally so designed that the throttle can move to a position corresponding to a vehicular speed of approximately 15-20 miles per hour before the valve 100 begins to move.

Whenever the throttle is opened the suction in the main air chamber is increased andthe main air valve 82 is opened to admit additional air and increase the quantity of mixture supplied to the engine. The opening of this valve must be temporarily retarded to prevent fluttering of the valve and to restrict the admission of air sufficiently to somewhat enrich the mixture during the acceleration period immediately following any opening of the throttle. For this purpose a dashpot is provided which comprises a cylinder 130 and a piston 132 slidable therein. This piston is secured to the lower end'of the valve stem 84 by a yielding connection, permitting motion of the valve stem relative to the piston under certain operating conditions, and comprising a plate 134, secured to the lower end of said valve stem, which engages a. spring 136 received between the plate and a ring 138 received in a slot 140 formed on the inside wall of the piston 132,

the ring being split to permit assembly of the parts. A check valve 142 is received in a valve cage 144 which permits a flow of fuel therethrough when the valve is open and is formedin a closure plate 146 which closes the lower end of the cylinder 130 and is held in position by the plate secured to the bottom of the casting 28, the valve cooperating with a passageway 148 formed in the plate 70, and operating to prevent a flow of fuel from the cylinder on downward movement of the piston while permitting a flow into said cylinder as the piston moves upwardly when the air valve moves toward closed position.

The yielding connection of the dashpot piston to the valve stem 84 is provided for the purpose of eliminating the retarding effect of the dashpct when the air valve is opened under certain operating conditions. It has been found that under certain circumstances the air valve cannot be retarded in its opening movement without resulting in the formation of too rich a mixture which will result in loading and irregular operation of ,the engine. For instance, if the vehicle on which the device is used is coasting down a hill with the throttle closed and the clutch engaged, the engine is running at relatively high speed and when the throttle is opened at the bottom of the hill it is opened primarily for the purpose of maintaining the speed of the engine or to increase such speed relatively little. Under these conditions, it is not desirable to remm the opening of the air valve and since the,

manifold vacuum under such operating conditions is very high, the opening of the throttle communicates a sufiicient degree of vacuum to the air chamber 95 to open the air valve with sufficient force to overcome the resistance of spring 136, whereby such spring'is collapsed and the air valve stem moves downwardly without accompanying movement of the dashpot piston. After the air valve comes to rest the force of the spring 136 will move the piston relatively slowly with respect to the valve stem until it assumes its original position as shown in Fig. 2. On any opening movement of the throttle, however, which does not communicate sufiicient suction to the air chamber to collapse the spring 136, the piston is moved downwardly through the medium of said spring simultaneously with the downward movement of the valve stem 84.

. In addition to the above described means for 125 retarding the opening of the air valve to enrich the mixture, there is provided a positively operated fuel pump comprising a cylinder 150 formed in the casting 28 and a cooperating piston 152, fitted relatively tightly in said cylinder 30 and provided with an upstanding piston rod 154 formed integrally therewith. The piston rod is provided with two ears 155 at its upper end pivotally connected by pin 156 to an operating link 158 pivotally connected at its upper end by 35 a pin 160 to the operating plate 116 as shown in Fig. 4. This piston is-obviously moved downwardly during the clockwise movement of the plate 116 which accompanies any opening movement of the throttle and on its downward movement the piston forces-fuel from the bottom of the cylinder 150 through a passage 162 into a chamber 164 formed in the casting 28 and in which a calibrated plug 166 is screwed as shown in Fig. 11. This plug forms a valve seat with which a check 145 valve 168, of square cross section and vertically reciprocable in a bore 1'70, cooperates. On the downward stroke of the pump piston the check valve is lifted and fuel is forced past said valve through a vertical fuel passage 172 into. a hori- 150 passages 1'78 and 183.

zontal channel 174 formed in the bottom wall of the main housing and which communicates with three channels 176, which are at right angles thereto and which communicate with three vertical passages 178, each of which communicates with one of the primary mixture passages '74" at the point adjacent the throttle valve 78, and terminates flush with the wall of said passage, said passages 1'78 each being provided with a restricted outlet 180 to regulate the flow into the mixture passages during the operation of the fuel pump.

Means are provided to admit air to the fuel being forced through the passages 178 by the fuel pump, comprising a tube 182 which is secured in the casting 28 and admits air from the space above the fuel in the float chamber to the horizontal channel 174 and a vertical passage 183 formed in the wall of the main housing and communicating with an orifice 184 also formed in the casting 28, which also communicates with the space above the fuel in the float chamber. Connecting the passage 183 with each of the passages 176 are passages 186 bored diagonally in the wall of the main housing with respect to the By admission of air to the fuel delivery passages leading from the pump to the primary mixture passages, an emulsion of fuel and air is formed therein which passes into said mixture passages on operation of the pump.

The means for admitting air to the pump delivery passages is provided for the purpose of preventing sufficient suction being communicated to such pump delivery passages to draw fuel therefrom at any time except during the downward movement of the pump piston. The tube 182 also permits a part of the fuel forced into chamber or channel 1'74 to return to the float chamber during the downward movement of the piston so as to limit to some extent the amount of additional fuel supplied by the pump.

According to this invention the fuel pump is employed to operate the valve 63 which controls the admission of additional fuel to the main fuel nozzles as previously described. For this purpose an arm 190 is received around the piston rod 154 between two flanges 192 and 194 formed thereon and at its other end is provided with'an opening in which the stem 69 of the valve 62 is received. The arm 190 is provided with a slot 198 nearly as large as the piston rod between the flanges and is preferably made of sufficiently elastic material to permit a slight widening of the slot as the arm is assembled in position on the piston rod, but closing the slot thereafter .enough to hold the arm in place. On downward motion of the pump pfiton accompanying any opening of the throttle the arm 190 moves downwardly without operating the valve 62 until said arm engages the enlargement '71 formed on the valve stem 69, thus opening said valve after the throttle has been opened a predetermined amount. In certain earlier devices of this character such as those disclosed in the earlier applications above referred to, it is necessary to begin the opening of the high speed fuel valve substantially simultaneously with the opening of the valve controlling admission of air through the secondary air passage, for the reason that the suction in the primary mixing chambers does not increase rapidly enough following the opening of this valve to effect a sufficient flow of fuel from the nozzles to compensate for the increased supply of air admitted to the secondary mixing chambers through said secondary air passage. In the device disclosed herein, however, a higher degree of suction is maintained in-the primary chambers for reasons set forth hereinafter, and the high speed fuel valve does not have to be opened until the-engine is operating at a speed corresponding to a vehicular speed of approximately forty miles per hour, on a level. This is of advantage becausethe action of the parts does not have to be so accurately synchronized, due to the fact that slight errors in synchronization produce less effect on the operation of the engine when the latter is running fast than when running at a lower rate of speed.

The reason for the above described action should be obvious. when the valve controlling the flow of air through the secondary air passage begins to open, the rate of increase in suction in the primary air chamber and the primary mixing chambers on opening of the throttle would be less than before the opening of said valve unless means be provided to off-set such action. Of course, there is a greater increase in the suction effective on the main air valve under such circumstances and this is made use of to prevent the above described condition in the primary air chamber and primary mixing chambers. Following any opening of the throttle when the valve controlling flow through the secondary air passage is also opened, the increase in suction effective on the main air valve causes it to open, compressing the valve spring and increasing the resistance to opening of the primary air valve to as great or greater degree than the force tending to open it is increased. In fact because of the difference in size of the air valves the primary air valve will be temporarily moved toward closed position following immediately upon the opening movement of the throttle. As the engine speeds up, however, as a result of the opening of the throttle the suction on the primary air valve is increased so that the valve is opened to some extent as well as the secondary air valve, the degree of opening of the two valves depending on the relative sizes thereof. This temporary closing movement of the primary air valve is effective to produce the desired enriched mixture during the acceleration period.

The secondary mixing chambers which are formed in each outlet branch of the manifold are not described herein, but may comprise any known means for straightening the flow of air past the ends of the primary mixture conduits and accelerating the flow of air at such points in order to create a high velocity of flow through said primary conduits. For example, the secondary mixing chambers may be of the form shown in either of the prior applications above referred to.

While the form of embodiment of the present invention as herein disclosed, constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as follows:

1. A charge forming device for internal combustion engines comprising a mixing chamber, means for supplying fuel and air thereto, a secondary air passage adapted to supply auxiliary air, a valve controlling admission of air through said passage, a throttle, a fuel pump for supplying additional fuel during the acceleration period, an operating member secured to the throttle andgoperalting connections extending from said member to the pump and said secondary air valve. 1

2. A charge forming device for internal combustion engines comprising a mixing chamber, means for supplying fuel and air thereto, a secondary air passage adapted to supply auxiliary air, a valve controlling admission of air through said passage, a throttle, a fuel pump for supplying additional fuel during the acceleration period, means for supplying additional fuel under certain operating conditions, a fuel valve for controlling said fuel supply means, a single operating member connected to the pump so as to operate said pump on every opening movement, an operating connection extending from said member to the air valve and adapted to operate the valve after the throttle has made a predetermined'opening movement, and means for operating the fuel valve as the throttle is opened.

3. A charge forming device for internal combustion engines comprising a mixing chamber, means for supplying fuel and air thereto, a secondary air passage adapted to supply auxiliary air, a valve controlling admission of air through said passage, a throttle, a fuel pump for supplying additional fuel during the acceleration period, other means for supplying additional fuel under certain operating conditions, a fuel valve for controlling said fuel supply means, a single operating member connected to the pump so as to operate said pump on every opening movement of the throttle, an operating connection extending from said member to the air valve and adapted to operate the valve after the throttle has made a predetermined opening movement, and means for operating the fuel valve substantially simultaneously with the air valve.

4. A charge forming device for internal combustion engines comprising a mixing chamber, means for supplying fuel and air thereto, a secondary air passage adapted to supply auxiliary air, a valve controlling admission of air through said passage, a throttle, a fuel pump for supplying additional fuel during the acceleration period,

other means for supplying additional fuel under certain operating conditions, a fuel valve for controlling said fuel supply means, a single operating member connected to the pump so as to operate said pump on every opening movement of the throttle, an operating connection extending from said member to the air valve and adapted to operate the valve after the throttle has made a predetermined opening movement and a member carried by the operating means for said pump and adapted to engage the fuel valve to open said valve substantially simultaneously with the air valve.

5. A charge forming device for internal combustion engines comprisinga mixing chamber, means for supplying fuel and air thereto, a secondary air passage adapted to supply auxiliary air, a valve controlling admission of air through said passage, a throttle, a fuel pump for supply-- ing additional fuel during the acceleration period,

other means for supplying additional fuel under certain operating conditions, a fuel valve for controlling said fuel supply means, a single operating member secured to the throttle and adapted to operate the pump and the secondary air valve, and a member carried by the operating means for said pump adapted to'engage said fuel valve during opening movement of the throttle.

6. A charge forming device for internal combustion engines comprising a secondary mixing chamber, a primarymixture passage adapted to deliver a primary mixture of fuel and air thereto, means for supplying fuel and air to said mixture passage, a primary throttle controlling the flow therethrough, a secondary air passage adapted to supply air to the secondary mixing chamber, a secondary throttle controlling the flow through said air passage, operating mechanism for the two throttles, s'aid mechanism including an operating link pivotally connected to the secondary throttle and so connected tothe primary throttle that it moves substantially in an are about its pivot point during a part of the movement of said primary throttle without moving the secondary throttle.

7. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air chambers for supplying air to said,

primary and secondary mixing chambers respectively, separate and independently operable valves for controlling the admission of air to said chambers, said valves being adapted to maintain different degrees of suction in said air chambers, and one of said valves being constructed to control the operation of the other of said valves.

8. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air chambers for supplying air to said primary and secondary mixing chambers respectively, separate and independently operable valves suction operated for controlling the admission of air to said air chambers, and one of said valves being constructed to control the operation of the other of said valves.

9. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air chambers for supplying air to said primary and secondary mixing chambers respectively, separate, and independently operable valves for regulating the admission of air to said primary and secondary air chambers, and a single means for closing said valves.

10. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air chambers for supplying air to said primary and secondary mixing chambers respectively, separate valves .for regulating the admission of air to said primary and secondary air chambers, and means for temporarily retarding the opening movement of the valve controlling the admission of air to said primary air chamber controlled by the opening movement of the secondary air valve.

11. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air chambers for supplying air to said primary and secondary mixing chambers respectively, separate and independently operable valves for regulating the admission of air to said primary and secondary air chambers and a single stem for supporting said valves.

12. A charge forming device for internal combustion engines comprising a plurality of secondary mixing chambers, a plurality of primary mixing chambers adapted to deliver a primary mixture of fuel and air thereto, a throttle, primary and secondary 'air chambers, said primary air chamber being constructed to communicate with all of the primary mixing chambers, a secondary air passage conveying air from the secondary air chamber to the secondary mixing chambers, and separate means for regulating the admission of air to said air chambers, said means being constructed to maintain different degrees of suction in said air chambers, one of said means being effective to control the operation of the other of said means.

13. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air chambers for supplying air to said primary and secondary mixing chambers respectively, separate and independently operable valves for regulating the admission of air to said primary and secondary air chambers and means whereby the opening of the valve admitting air to the secondary mixing chamber effects a temporary closing movement of the valve admitting air to the primary mixing chamber.

14. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air inlets for supplying air to said primary and secondary mixing chambers respectively, separate and independently operable valves for regulating the admission of air through said inlets, and a single stem for supporting said valves, said valves being movable on said stem.

15. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air inlets for supplying air to said primary and secondary mixing chambers respectively, separate and independently operable suction operated valves for regulating the admission of air through said inlets, and a single stem for supporting said valves 16. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air inlets for supplying air to said primary and secondary mixing chambers respectively, separate and independently operable suction operated valves for regulating the admission of air through said inlets, a single stem for supporting said valves and a spring common to both said valves for controlling the opening movement thereof.

1'7. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air inlets for supplying air to said primary and secondary mixing chambers respectively, separate and independently operable valves for regulating the admission of air through said inlets, a single stem for movably supporting said valves, and a single means for controlling the opening movement of both said valves.

18. A charge forming device for internal combustion engines comprising a primary mixing chamber, means for supplying fuel and air thereto, a throttle, a secondary mixing chamber into which the primary mixing chamber delivers a primary mixture of fuel and air, primary and secondary air inlets for admitting air to said primary and secondary air chambers respectively, separate and independently operable primary and secondary air valves for regulating the admission of air through said primary and secondary air inlets, a single valve stem supporting said air valves, and means for holding said primary air valve closed while permitting opening of the secondary air valve to facilitate starting of the engine.

CRAIG V. MORTON. 

